Fothergill



JOHN BRADBURNE DODDS, OF NEWCASTLE-ON-TYNE, AND JOHN REED FOTHERGlLT -OFVV'EST I 'IARTLEPOOL, ENGLAND.

INCRUSTATION PREVENTIVE.

SPECIFICATION formingpart of Letters Patent No. 477,357, dated June 21,1892. Application filed May 15, 1891. Serial No. 392,886. (Nospecimens.) Patented in England June 8, 1889, No. 9,573.

To all whom it may concern.-

Be it known that we, JOHN BRADBURNE DODDS, residing atNewcastle-on-Tyne, in the county of Northumberland, and JOHN REEDFOTHERGILL, residing at Vest Hartlepool,in the county of Durham,England, subjects of the Queen of Great Britain andlreland, haveinvented the manufacture and application of a certain fluid preparationfor preventing or lessening corrosion and pitting in steamboilers, (forwhich we have obtained a British patent, No. 9,573, dated June 8, 1889,)of which the following is a specification.

As is well known, corrosion and pitting occurin the interiors ofsteam-boilers, and various means have been resorted to with the view ofobviating the evil. One of these, which is adopted especially inmarine-boilers, consists in placing inside the boiler, either suspendedin trays or hangers or fastened. to and in metallic contact with themetal of the boiler or applied in some other manner or form, slabs,blocks, or plates of zinc. These have been found to exercise abeneficial influence to a certain extent, but are open to the objectionthat the whole of the zinc required must be placed in the boiler beforeclosing up and filling the boiler with water. Itresults that during thefirst few days steaming there is a large quantity of zinc very active.Then from various causes-for instance, oxidationthe zinc ceases to beeffective just when it is required to act most efficientlythat is tosay, as the source or cause of corrosion becomes more active, which itdoes the longer the boiler is under continuous steam. Now in order toobviate this difficulty according to our invention, we manufacture zincsolution, as hereinafter described, and apply the same to steam-boilersat regular or stated intervals, either with the feedwater by a separatepump or by injection or by other similar or suitable methods, by whichmeans we are enabled to provide and maintain a steady, constant, andeffective preventive to corrosion, and thereby to preserve the boilersfrom corrosion and pitting; or the solution may when thickened, ashereinafter described, be used as a wash or paint, applied by a brush orin some other convenient and similar manner to particular corroded orpitted places in the boiler while the water is out of the boiler or tothe material of new boilers, during construction.

In the manufacture of the zinc solution we add to water suitablequantities of sodic hydrate (NaHO) or potassic hydrate (KHQ) and ofzinc. (Zn) rendered sufficiently small to be readily soluble, and weheat the whole until the sodic hydrate or potassic hydrate, as thecase-may be, has dissolved its full proportion of zinc, after which morewater is added and the whole allowed to cool and settle, and the clearliquor is drawn olf for use according to our invention; or, instead ofmetallic zinc, as described, galvanized iron may be used, out intoconvenient-sized pieces to facilitate the operation. The sodic hydrateor potassic hydrate, as described, will dissolve the zinc and leave theiron intact; or, zinc salts may be used, in which case ammonic hydrate(H NHO) could be substituted for sodic or potassic hydrate.

In carrying out this invention satisfactory results may be obtained bythe use of an open or covered or closed iron vessel, capable of holdingany desired quantity of liquor, which is fixed in a convenient position,such as to admit of the ready application of constant and steady heateither by gas,- fire, or steam. For the purpose of illustration, say,the iron vessel holds one hundred gallons. \Ve place about fifty gallonsof clean water in this vessel and add thereto about one hundred andsixty-eight pounds sodic hydrate (NaHO) or potassic hydrate (KI-TO) andabout fifty-six pounds of zinc (Zn), the zinc being first feathered bymelting and pouring into water or in some other of the various knownmethods, whereby it is caused to present extended surfaces and sofacilitates its solution, or galvanized iron out in convenient-sizedpieces may be substituted for the zinc. Heat is gradually applied to thevessel, and a temperature of about 212 Fahrenheit maintained for aboutten hours, or until the sodic hydrate or potassic hydrate, depending onthe percentage of sodic oxide (Na O) or potassic oxide (K 0),respectively, which they contain, shall have dissolved its fullproportion of zinc. y

when zinc salts are used, ammonia hydrate may be substituted for sodicor potassic hydrate. The effect of this will be to precipitate hydratedoxide of zinc hereinafter referred to as the zinc base derived from azinc salt and which when the mixture is heated will be dissolved in theammonic hydrate. The vessel is then filled up with clean water, so thatthe whole measures one hundred gallons. The heat is withdrawn and theliquor allowed to cool down and settle, when the clear liquor is drawnolf, which, as already stated, constitutes the zinc solution inaccordance with our invention forapplication to steam-boilers whileunder steam; but when the solution is required to be used as a wash orpaint it may be thickened by mixing with it Portland cement or lime orother similar substances, which will adhere to the material of theboiler and which in themselves are not corrosive, or the solution may beevaporated JOHN BRADBURNE DODDS. JOHN REED FOTI-IERGILL.

Witnesses:

A. B. GOLDSBROUGH, No. 234 Hamilton street, Newcastle-on-Tyne,

Solicitors O'leflc.

A. E. DAWSON, Belle Vue Road, Low Fen, Galesheacl, Solicitors Clerk.

